I've seen this recently with video4linux installed with the 2.6.19
kernel. cx88-dvb is probably not running. Open a terminal window and
type su (enter) and the root passsword (enter) Then type:
lsmod | grep cx88
If you don't see cx88-dvb listed, that's your problem.
First try typing
modprobe cx88-dvb (enter)
Close the terminal window and open a file manager and take a look in
/dev. You should now have /dev/dvb/adapter0, but also make sure your
/video0,1 and 2 are all still there. If they are, then (as root)add a
modprobe cx88-dvb statement to the end of /etc/rc.d/rc.local, save it
and reboot. You should be all set.
If one of your /dev/videos disappeared, add the following to rc.local
modprobe -r cx8802
modprobe cx88-dvb
Then save and reboot. You should be good to go.
The moral of this story is of course, if it works - don't fix it! ;)